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LOAD FLOW ACTIVITY DESCRIPTIONS Siemens Power Transmission & Distribution, Inc.READ Power Technologies International

4-6 PROGRAM OPERATION MANUAL: VOLUME I PSS/E-30.1

4.1 Activity READThe bulk power flow data input activity, READ, picks up hand-typed power flow source data and enters it into the load flow working case, rearranging it from its original format into a computation-ally oriented data structure in the process. The source data records may be input from a Power Flow Raw Data File (the normal case) or from the dialog input device (console keyboard or Response File).

All data is read in "free format" with data items separated by a comma or one or more blanks. Each category of data, except the case identification data, is terminated by a record specifying an "I" value of zero.

4.1.1 Power Flow Raw Data File ContentsThe input stream to activity READ consists of 17 groups of records, with each group containing a particular type of data required in power flow work (see Figure 4-1).

For data records described in Sections 4.1.1.3 through 4.1.1.10, 4.1.1.12, 4.1.1.13, and 4.1.1.17, those data items that designate ac buses may be specified as either extended bus names enclosed in single quotes or bus numbers when the suffix NAME is specified when selecting activity READ (see Section 4.1.2) or when the "Names" input option is selected in the GUI dialog. Otherwise, bus numbers must be used to designate ac buses on these data records.

4.1.1.1 Case Identification Data

Case identification data consists of three data records. The first record contains two items of data as follows:

IC, SBASE

where:

IC Change code: 0 - base case (i.e., clear the working case before adding data to it)1 - add data to the working caseIC = 0 by default.

SBASE System base MVA. SBASE = 100.0 by default.

The next two records each contain a line of heading to be associated with the case. Each line may contain up to 60 characters, which are typed in columns 1 through 60.

PSS/E-30.1 PROGRAM OPERATION MANUAL: VOLUME I 4-7

Siemens Power Transmission & Distribution, Inc. LOAD FLOW ACTIVITY DESCRIPTIONS

Power Technologies International READ

Figure 4-1. Power Flow Raw Data Input Structure

Voltage Source Converter dc Line Data

Zone Data

Generator Data

Nontransformer Branch Data

Multisection Line Grouping Data

Area Interchange Data

Two-Terminal dc Line Data

Switched Shunt Data

Transformer Impedance Correction Tables

Multi-Terminal dc Line Data

Load Data

Transformer Data

Interarea Transfer Data

Case Identification

Bus Data

Owner Data

FACTS Device Data



4.1.1.2 Bus Data

Each network bus to be represented in PSS/E is introduced by reading a bus data record. Each bus data record has the following format:

I, 'NAME', BASKV, IDE, GL, BL, AREA, ZONE, VM, VA, OWNER

where:

I Bus number (1 through 999997).

NAME Alphanumeric identifier assigned to bus "I". The name may be up to twelve char-acters and must be enclosed in single quotes. NAME may contain any combination of blanks, uppercase letters, numbers and special characters, but the first character must not be a minus sign. NAME is twelve blanks by default.

BASKV Bus base voltage; entered in kV. BASKV = 0.0 by default.

IDE Bus type code: 1 - load bus (no generator boundary condition) 2 - generator or plant bus (either voltage regulating or fixed Mvar) 3 - swing bus 4 - disconnected (isolated) bus IDE = 1 by default.

GL Active component of shunt admittance to ground; entered in MW at one per unit voltage. GL should not include any resistive impedance load, which is entered as part of load data. GL = 0.0 by default.

BL Reactive component of shunt admittance to ground; entered in Mvar at one per unit voltage. BL should not include any reactive impedance load, which is entered as part of load data; line charging and line connected shunts, which are entered as part of non-transformer branch data; or transformer magnetizing admittance, which is entered as part of transformer data. BL is positive for a capacitor, and negative for a reactor or an inductive load. BL = 0.0 by default.

AREA Area number (1 through the maximum number of areas at the current size level; see Table P-1). AREA = 1 by default.

ZONE Zone number (1 through the maximum number of zones at the current size level; see Table P-1). ZONE = 1 by default.

VM Bus voltage magnitude; entered in pu. VM = 1.0 by default.

VA Bus voltage phase angle; entered in degrees. VA = 0.0 by default.

OWNER Owner number (1 through the maximum number of owners at the current size level; see Table P-1). OWNER = 1 by default.




VM and VA need to be set to their actual solved case values only when the network, as entered into the working case via activity READ, is to be considered solved as read in. Otherwise, they may be set to their default values.

Bus data input is terminated with a record specifying a bus number of zero.

4.1.1.3 Load Data

Each network bus at which load is to be represented must be specified in at least one load data record. Each load data record has the following format:

I, ID, STATUS, AREA, ZONE, PL, QL, IP, IQ, YP, YQ, OWNER

where:

I Bus number, or extended bus name enclosed in single quotes (see Section 4.1.2).

ID One- or two-character uppercase nonblank alphanumeric load identifier used to distinguish among multiple loads at bus "I". It is recommended that, at buses for which a single load is present, the load be designated as having the load identifier ’1’. ID = ’1’ by default.

STATUS Initial load status of one for in-service and zero for out-of-service. STATUS = 1 by default.

AREA Area to which the load is assigned (1 through the maximum number of areas at the current size level; see Table P-1). By default, AREA is the area to which bus "I" is assigned (see Section 4.1.1.2).

ZONE Zone to which the load is assigned (1 through the maximum number of zones at the current size level; see Table P-1). By default, ZONE is the zone to which bus "I" is assigned (see Section 4.1.1.2).

PL Active power component of constant MVA load; entered in MW. PL = 0.0 by default.

QL Reactive power component of constant MVA load; entered in Mvar. QL = 0.0 by default.

IP Active power component of constant current load; entered in MW at one per unit voltage. IP = 0.0 by default.

IQ Reactive power component of constant current load; entered in Mvar at one per unit voltage. IQ = 0.0 by default.

YP Active power component of constant admittance load; entered in MW at one per unit voltage. YP = 0.0 by default.

YQ Reactive power component of constant admittance load; entered in Mvar at one per unit voltage. YQ is a negative quantity for an inductive load. YQ = 0.0 by default.



OWNER Owner to which the load is assigned (1 through the maximum number of owners at the current size level; see Table P-1). By default, OWNER is the owner to which bus "I" is assigned (see Section 4.1.1.2).

Multiple loads may be represented at a bus by specifying more than one load data record for the bus, each with a different load identifier. The area, zone, and owner assignments of loads are used for area, zone, and owner totaling purposes (e.g., in activities AREA, ZONE, and OWNR) and for load scaling and conversion purposes. They may differ from those of the bus to which they are connected. The area and zone assignments of loads may optionally be used during area and zone interchange calculations (see Section 4.10.3.3, and Sections 4.46 through 4.51).

Further details on load characteristic modeling are given in Sections 4.8.3, 4.16, and 4.17.

Load data input is terminated with a record specifying a bus number of zero.

4.1.1.4 Generator Data

Each network bus to be represented as a generator or plant bus in PSS/E must be specified in a generator data record. In particular, each bus specified in the bus data input with a type code of two or three must have a generator data record entered for it. Each generator data record has the fol-lowing format:

I,ID,PG,QG,QT,QB,VS,IREG,MBASE,ZR,ZX,RT,XT,GTAP,STAT,RMPCT,PT,PB,O1,F1,...,O4,F4

where:


ID One- or two-character uppercase nonblank alphanumeric machine identifier used to distinguish among multiple machines at bus "I". It is recommended that, at buses for which a single machine is present, the machine be designated as having the machine identifier ’1’. ID = ’1’ by default.

PG Generator active power output; entered in MW. PG = 0.0 by default.

QG Generator reactive power output; entered in Mvar. QG need be entered only if the case, as read in, is to be treated as a solved case. QG = 0.0 by default.

QT Maximum generator reactive power output; entered in Mvar. For fixed output gen-erators (i.e., nonregulating), QT must be equal to the fixed Mvar output. QT = 9999.0 by default.

QB Minimum generator reactive power output; entered in Mvar. For fixed output generators, QB must be equal to the fixed Mvar output. QB = -9999.0 by default.

VS Regulated voltage setpoint; entered in pu. VS = 1.0 by default.

IREG Bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of a remote type 1 or 2 bus whose voltage is to be regulated by this plant to the value specified by VS. If bus IREG is other than a type 1 or 2 bus, bus I regulates its own voltage to the value specified by VS. IREG is entered as zero if the plant is




to regulate its own voltage and must be zero for a type three (swing) bus. IREG = 0 by default.

MBASE Total MVA base of the units represented by this machine; entered in MVA. This quantity is not needed in normal power flow and equivalent construction work, but is required for switching studies, fault analysis, and dynamic simulation. MBASE = system base MVA by default.

ZR,ZX Complex machine impedance, ZSORCE; entered in pu on MBASE base. This data is not needed in normal power flow and equivalent construction work, but is required for switching studies, fault analysis, and dynamic simulation. For dynamic simulation, this impedance must be set equal to the subtransient imped-ance for those generators to be modeled by subtransient level machine models, and to transient impedance for those to be modeled by classical or transient level models. ZR = 0.0 and ZX = 1.0 by default.

RT,XT Step-up transformer impedance, XTRAN; entered in pu on MBASE base. XTRAN should be entered as zero if the step-up transformer is explicitly modeled as a net-work branch and bus I is the terminal bus. RT+jXT = 0.0 by default.

GTAP Step-up transformer off-nominal turns ratio; entered in pu. GTAP is used only if XTRAN is nonzero. GTAP = 1.0 by default.

STAT Initial machine status of one for in-service and zero for out-of-service; STAT = 1 by default.

RMPCT Percent of the total Mvar required to hold the voltage at the bus controlled by bus I that are to be contributed by the generation at bus I; RMPCT must be positive. RMPCT is needed only if IREG specifies a valid remote bus and there is more than one local or remote voltage controlling device (plant, switched shunt, FACTS device shunt element, or VSC dc line converter) controlling the voltage at bus IREG to a setpoint, or IREG is zero but bus I is the controlled bus, local or remote, of one or more other setpoint mode voltage controlling devices. RMPCT = 100.0 by default.

PT Maximum generator active power output; entered in MW. PT = 9999.0 by default.

PB Minimum generator active power output; entered in MW. PB = -9999.0 by default.

Oi Owner number (1 through the maximum number of owners at the current size level; see Table P-1). Each machine may have up to four owners. By default, O1 is the owner to which bus "I" is assigned (see Section 4.1.1.2) and O2, O3, and O4 are zero.

Fi Fraction of total ownership assigned to owner Oi; each Fi must be positive. The Fi values are normalized such that they sum to 1.0 before they are placed in the working case. By default, each Fi is 1.0.

In specifying reactive power limits for voltage controlling plants (i.e., those with unequal reactive power limits), the use of very narrow var limit bands is discouraged. The Newton-Raphson based



power flow solutions require that the difference between the controlling equipment's high and low reactive power limits be greater than 0.002 pu for all setpoint mode voltage controlling equipment (0.2 Mvar on a 100 MVA system base). It is recommended that voltage controlling plants have Mvar ranges substantially wider than this minimum permissible range.

When two or more machines are to be separately modeled at a plant, their data may be introduced into the working case using one of two approaches.

A generator data record may be entered in activities READ, TREA, or RDCH for each of the machines to be represented, with machine powers, power limits, impedance data, and step-up trans-former data for each machine specified on separate generator data records. The plant power output and power limits are taken as the sum of the corresponding quantities of the in-service machines at the plant. The values specified for VS, IREG, and RMPCT, which are treated as plant quantities rather than individual machine quantities, must be identical on each of these generator data records.

Alternatively, a single generator record may be specified in activities READ, TREA, or RDCH with the plant total power output, power limits, voltage setpoint, remotely regulated bus, and percent of contributed Mvar entered. Impedance and step-up transformer data may be omitted. The PSS/E power flow activities may be used and then, any time prior to beginning switching study, fault analysis, or dynamic simulation work, activity MCRE may be used to introduce the individual machine impedance and step-up transformer data; activity MCRE also apportions the total plant loading among the individual machines (see Section 4.4).

Further details on generator modeling in power flow solutions are given in Sections 4.8.2 and 4.8.7.

Generator data input is terminated with a record specifying a bus number of zero.

4.1.1.5 Nontransformer Branch Data

Each ac network branch to be represented in PSS/E as a nontransformer branch is introduced by reading a nontransformer branch data record. (Data records for transformers are entered in the trans-former data category described in Section 4.1.1.6.) Each nontransformer branch data record has the following format:

I,J,CKT,R,X,B,RATEA,RATEB,RATEC,GI,BI,GJ,BJ,ST,LEN,O1,F1,...,O4,F4

where:

I Branch "from bus" number, or extended bus name enclosed in single quotes (see Section 4.1.2).

J Branch "to bus" number, or extended bus name enclosed in single quotes (see Section 4.1.2). J is entered as a negative number, or with a minus sign before the first character of the extended bus name, to designate it as the metered end; other-wise, bus I is assumed to be the metered end.

CKT One- or two-character uppercase nonblank alphanumeric branch circuit identifier; the first character of CKT must not be an ampersand ("&"); see Section 4.1.1.13. It is recommended that single circuit branches be designated as having the circuit identifier ’1’. CKT = ’1’ by default.




R Branch resistance; entered in pu. A value of R must be entered for each branch.

X Branch reactance; entered in pu. A nonzero value of X must be entered for each branch. See Section 4.1.4 for details on the treatment of branches as zero imped-ance lines.

B Total branch charging susceptance; entered in pu. B = 0.0 by default.

RATEA First current rating; entered in MVA. RATEA = 0.0 (bypass check for this branch) by default. See also Section 4.53.

RATEB Second current rating; entered in MVA. RATEB = 0.0 by default.

RATEC Third current rating; entered in MVA. RATEC = 0.0 by default.

GI,BI Complex admittance of the line shunt at the bus "I" end of the branch; entered in pu. BI is negative for a line connected reactor. GI + jBI = 0.0 by default.

GJ,BJ Complex admittance of the line shunt at the bus "J" end of the branch; entered in pu. BJ is negative for a line connected reactor. GJ + jBJ = 0.0 by default.

ST Initial branch status where 1 designates in-service and 0 designates out-of-service. ST = 1 by default.

LEN Line length; entered in user-selected units. LEN = 0.0 by default.

Oi Owner number (1 through the maximum number of owners at the current size level; see Table P-1). Each branch may have up to four owners. By default, O1 is the owner to which bus "I" is assigned (see Section 4.1.1.2) and O2, O3, and O4 are zero.

Fi Fraction of total ownership assigned to owner Oi; each Fi must be positive. The Fi values are normalized such that they sum to 1.0 before they are placed in the working case. By default, each Fi is 1.0.

When specifying a nontransformer branch between buses I and J with circuit identifier CKT, if a two-winding transformer between buses I and J with a circuit identifier of CKT is already present in the working case, it is replaced (i.e., the transformer is deleted from the working case and the newly specified branch is then added to the working case).

Note again that branches to be modeled as transformers are not specified in this data category; rather, they are specified in the transformer data category described in Section 4.1.1.6.

Nontransformer branch data input is terminated with a record specifying a "from bus" number of zero.

4.1.1.6 Transformer Data

Each ac transformer to be represented in PSS/E is introduced by reading a transformer data record block. Transformer data record blocks specify all the data needed to model transformers in power flow calculations. Both two-winding transformers and three-winding transformers are specified in transformer data record blocks; two-winding transformers require a block of four data records, and three-winding transformers require five data records.



The five record transformer data block for three-winding transformers has the following format:

I,J,K,CKT,CW,CZ,CM,MAG1,MAG2,NMETR,’NAME’,STAT,O1,F1,...,O4,F4R1-2,X1-2,SBASE1-2,R2-3,X2-3,SBASE2-3,R3-1,X3-1,SBASE3-1,VMSTAR,ANSTARWINDV1,NOMV1,ANG1,RATA1,RATB1,RATC1,COD1,CONT1,RMA1,RMI1,VMA1,VMI1,NTP1,TAB1,CR1,CX1WINDV2,NOMV2,ANG2,RATA2,RATB2,RATC2,COD2,CONT2,RMA2,RMI2,VMA2,VMI2,NTP2,TAB2,CR2,CX2WINDV3,NOMV3,ANG3,RATA3,RATB3,RATC3,COD3,CONT3,RMA3,RMI3,VMA3,VMI3,NTP3,TAB3,CR3,CX3

The four-record transformer data block for two-winding transformers is a subset of the data required for three-winding transformers and has the following format:

I,J,K,CKT,CW,CZ,CM,MAG1,MAG2,NMETR,’NAME’,STAT,O1,F1,...,O4,F4R1-2,X1-2,SBASE1-2WINDV1,NOMV1,ANG1,RATA1,RATB1,RATC1,COD1,CONT1,RMA1,RMI1,VMA1,VMI1,NTP1,TAB1,CR1,CX1WINDV2,NOMV2

Control parameters for the automatic adjustment of transformers and phase shifters are specified on the third record of the two-winding transformer data block, and on the third through fifth records of the three-winding transformer data block. All transformers are adjustable and the control parame-ters may be specified either at the time of raw data input or subsequently via activities CHNG or XLIS, or the data editor windows. Any two-winding transformer and any three-winding transformer winding for which no control data is provided has default data assigned to it; the default data is such that the two-winding transformer or three-winding transformer winding is treated as fixed.

See Section 4.1.2.6 and 4.1.5 for further details on the three-winding transformer model used in PSS/E.

All data items on the first record are specified for both two- and three-winding transformers:

I The bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the bus to which the first winding is connected. The trans-former’s magnetizing admittance is modeled on winding one. The first winding is the only winding of a two-winding transformer whose tap ratio or phase shift angle may be adjusted by the power flow solution activities; any winding(s) of a three-winding transformer may be adjusted. No default is allowed.

J The bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the bus to which the second winding is connected. No default is allowed.

K The bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the bus to which the third winding is connected. Zero is used to indicate that no third winding is present (i.e., that a two-winding rather than a three-winding transformer is being specified). K = 0 by default.

CKT One- or two-character uppercase nonblank alphanumeric transformer circuit identifier; the first character of CKT must not be an ampersand ("&"); see Section 4.1.1.13. CKT = ’1’ by default.

CW The winding data I/O code which defines the units in which WINDV1, WINDV2 and WINDV3 are specified (the units of RMAn and RMIn are also




governed by CW when |CODn| is 1 or 2): 1 for off-nominal turns ratio in pu of winding bus base voltage; 2 for winding voltage in kV. CW = 1 by default.

CZ The impedance data I/O code that defines the units in which R1-2, X1-2, R2-3, X2-3, R3-1 and X3-1 are specified: 1 for resistance and reactance in pu on system base quantities; 2 for resistance and reactance in pu on a specified base MVA and winding base voltage; 3 for transformer load loss in watts and impedance magnitude in pu on a specified base MVA and winding base voltage. CZ = 1 by default.

CM The magnetizing admittance I/O code that defines the units in which MAG1 and MAG2 are specified: 1 for complex admittance in pu on system base quan-tities; 2 for no load loss in watts and exciting current in pu on winding one to two base MVA and nominal voltage. CM = 1 by default.

MAG1, MAG2 The magnetizing conductance and susceptance, respectively, in pu on system base quantities when CM is 1; MAG1 is the no load loss in watts and MAG2 is the exciting current in pu on winding one to two base MVA (SBASE1-2) and nominal voltage (NOMV1) when CM is 2. MAG1 = 0.0 and MAG2 = 0.0 by default.

When CM is 1 and a non-zero MAG2 is specified, MAG2 should be entered as a negative quantity; when CM is 2 and a non-zero MAG2 is specified, MAG2 should always be entered as a positive quantity.

NMETR The nonmetered end code of either 1 (for the winding one bus) or 2 (for the winding two bus). In addition, for a three-winding transformer, 3 (for the winding three bus) is a valid specification of NMETR. NMETR = 2 by default.

NAME An alphanumeric identifier assigned to the transformer. The name may be up to twelve characters and must be enclosed in single quotes. NAME may con-tain any combination of blanks, uppercase letters, numbers and special characters. NAME is twelve blanks by default.

STAT The initial transformer status, where 1 designates in-service and 0 designates out-of-service. In addition, for a three-winding transformer, 2 designates that only winding two is out-of-service, 3 indicates that only winding three is out-of-service, and 4 indicates that only winding one is out-of-service, with the remaining windings in-service. STAT = 1 by default.

Oi An owner number (1 through the maximum number of owners at the current size level; see Table P-1). Each transformer may have up to four owners. By default, O1 is the owner to which bus I is assigned and O2, O3, and O4 are zero.

Fi The fraction of total ownership assigned to owner Oi; each Fi must be positive. The Fi values are normalized such that they sum to 1.0 before they are placed in the working case. By default, each Fi is 1.0.

The first three data items on the second record are read for both two- and three-winding trans-formers; the remaining data items are used only for three-winding transformers:



R1-2, X1-2 The measured impedance of the transformer between the buses to which its first and second windings are connected. When CZ is 1, they are the resistance and reactance, respectively, in pu on system base quantities; when CZ is 2, they are the resistance and reactance, respectively, in pu on winding one to two base MVA (SBASE1-2) and winding one base voltage; when CZ is 3, R1-2 is the load loss in watts, and X1-2 is the impedance magnitude in pu on winding one to two base MVA (SBASE1-2) and winding base voltage. R1-2 = 0.0 by default, but no default is allowed for X1-2.

SBASE1-2 The winding one to two base MVA of the transformer. SBASE1-2 = SBASE (the system base MVA) by default.

R2-3, X2-3 The measured impedance of a three-winding transformer between the buses to which its second and third windings are connected; ignored for a two-winding transformer. When CZ is 1, they are the resistance and reactance, respectively, in pu on system base quantities; when CZ is 2, they are the resistance and reac-tance, respectively, in pu on winding two to three base MVA (SBASE2-3) and winding two base voltage; when CZ is 3, R2-3 is the load loss in watts, and X2-3 is the impedance magnitude in pu on winding two to three base MVA (SBASE2-3) and winding base voltage. R2-3 = 0.0 by default, but no default is allowed for X2-3.

SBASE2-3 The winding two to three base MVA of a three-winding transformer; ignored for a two-winding transformer. SBASE2-3 = SBASE (the system base MVA) by default.

R3-1, X3-1 The measured impedance of a three-winding transformer between the buses to which its third and first windings are connected; ignored for a two-winding transformer. When CZ is 1, they are the resistance and reactance, respectively, in pu on system base quantities; when CZ is 2, they are the resistance and reactance, respectively, in pu on winding three to one base MVA (SBASE3-1) and winding three base voltage; when CZ is 3, R3-1 is the load loss in watts, and X3-1 is the impedance magnitude in pu on winding three to one base MVA (SBASE3-1) and winding base voltage. R3-1 = 0.0 by default, but no default is allowed for X3-1.

SBASE3-1 The winding three to one base MVA of a three-winding transformer; ignored for a two-winding transformer. SBASE3-1 = SBASE (the system base MVA) by default.

VMSTAR The voltage magnitude at the hidden "star point" bus; entered in pu. VMSTAR = 1.0 by default.

ANSTAR The bus voltage phase angle at the hidden "star point" bus; entered in degrees. ANSTAR = 0.0 by default.




All data items on the third record are read for both two- and three-winding transformers:

WINDV1 The winding one off-nominal turns ratio in pu of winding one bus base voltage when CW is 1; WINDV1 = 1.0 by default. WINDV1 is the actual winding one voltage in kV when CW is 2; WINDV1 is equal to the base voltage of bus I by default.

NOMV1 The nominal (rated) winding one voltage in kV, or zero to indicate that nominal winding one voltage is to be taken as the base voltage of bus I. NOMV1 is used only in converting magnetizing data between per unit admittance values and physical units when CM is 2. NOMV1 = 0.0 by default.

ANG1 The winding one phase shift angle in degrees. ANG1 is positive for a positive phase shift from the winding one side to the winding two side (for a two-winding transformer), or from the winding one side to the "T" (or "star") point bus (for a three-winding transformer). ANG1 must be greater than -180.0 and less than or equal to +180.0. ANG1 = 0.0 by default.

RATA1, RATB1, The first winding’s three ratings entered in MVA (not current expressed inRATC1 MVA). RATA1 = 0.0, RATB1 = 0.0 and RATC1 = 0.0 (bypass flow limit

check for this transformer winding) by default.

COD1 The transformer control mode for automatic adjustments of the winding one tap or phase shift angle during power flow solutions: 0 for no control (fixed tap and phase shift); ±1 for voltage control; ±2 for reactive power flow control; ±3 for active power flow control; ±4 for control of a dc line quantity (+4 is valid only for two-winding transformers). If the control mode is entered as a positive number, automatic adjustment of this transformer winding is enabled when the corresponding adjustment is activated during power flow solutions; a negative control mode suppresses the automatic adjustment of this transformer winding. COD1 = 0 by default.

CONT1 The bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the bus whose voltage is to be controlled by the transformer turns ratio adjustment option of the power flow solution activities when COD1 is 1. CONT1 should be nonzero only for voltage controlling transformer windings.

CONT1 may specify a bus other than I, J, or K; in this case, the sign of CONT1 defines the location of the controlled bus relative to the transformer winding. If CONT1 is entered as a positive number, or a quoted extended bus name, the ratio is adjusted as if bus CONT1 is on the winding two or winding three side of the transformer; if CONT1 is entered as a negative number, or a quoted extended bus name with a minus sign preceding the first character, the ratio is adjusted as if bus |CONT1| is on the winding one side of the transformer. CONT1 = 0 by default.

RMA1, RMI1 The upper and lower limits, respectively, of either:

• Off-nominal turns ratio in pu of winding one bus base voltage when |COD1| is 1 or 2 and CW is 1; RMA1 = 1.1 and RMI1 = 0.9 by default.



• Actual winding one voltage in kV when |COD1| is 1 or 2 and CW is 2. No default is allowed.

• Phase shift angle in degrees when |COD1| is 3. No default is allowed.

• Not used when |COD1| is 0 or 4; RMA1 = 1.1 and RMI1 = 0.9 by default.

VMA1, VMI1 The upper and lower limits, respectively, of either:

• Voltage at the controlled bus (bus |CONT1|) in pu when |COD1| is 1. VMA1 = 1.1 and VMI1 = 0.9 by default.

• Reactive power flow into the transformer at the winding one bus end in Mvar when |COD1| is 2. No default is allowed.

• Active power flow into the transformer at the winding one bus end in MW when |COD1| is 3. No default is allowed.

• Not used when |COD1| is 0 or 4; VMA1 = 1.1 and VMI1 = 0.9 by default.

NTP1 The number of tap positions available; used when COD1 is 1 or 2. NTP1 must be between 2 and 9999. NTP1 = 33 by default.

TAB1 The number of a transformer impedance correction table if this transformer winding’s impedance is to be a function of either off-nominal turns ratio or phase shift angle (see Section 4.1.1.11), or 0 if no transformer impedance cor-rection is to be applied to this transformer winding. TAB1 = 0 by default.

CR1, CX1 The load drop compensation impedance for voltage controlling transformers entered in pu on system base quantities; used when COD1 is 1. CR1 + j CX1 = 0.0 by default.

The first two data items on the fourth record are read for both two- and three-winding transformers; the remaining data items are used only for three-winding transformers:

WINDV2 The winding two off-nominal turns ratio in pu of winding two bus base voltage when CW is 1; WINDV2 = 1.0 by default. WINDV2 is the actual winding two voltage in kV when CW is 2; WINDV2 is equal to the base voltage of bus J by default.

NOMV2 The nominal (rated) winding two voltage in kV, or zero to indicate that nom-inal winding two voltage is to be taken as the base voltage of bus J. NOMV2 is present for information purposes only; it is not used in any of the calculations for modeling the transformer. NOMV2 = 0.0 by default.

ANG2 The winding two phase shift angle in degrees; ignored for a two-winding trans-former. ANG2 is positive for a positive phase shift from the winding two side to the "T" (or "star") point bus. ANG2 must be greater than -180.0 and less than or equal to +180.0. ANG2 = 0.0 by default.

RATA2, RATB2, The second winding’s three ratings entered in MVA (not current expressed




RATC2 in MVA); ignored for a two-winding transformer. RATA2 = 0.0, RATB2 = 0.0 and RATC2 = 0.0 (bypass flow limit check for this transformer winding) by default.

COD2 The transformer control mode for automatic adjustments of the winding two tap or phase shift angle during power flow solutions: 0 for no control (fixed tap and phase shift); ±1 for voltage control; ±2 for reactive power flow control; ±3 for active power flow control. If the control mode is entered as a positive number, automatic adjustment of this transformer winding is enabled when the corresponding adjustment is activated during power flow solutions; a negative control mode suppresses the automatic adjustment of this transformer winding. COD2 = 0 by default.


CONT2 may specify a bus other than I, J, or K; in this case, the sign of CONT2 defines the location of the controlled bus relative to the transformer winding. If CONT2 is entered as a positive number, or a quoted extended bus name, the ratio is adjusted as if bus CONT2 is on the winding one or winding three side of the transformer; if CONT2 is entered as a negative number, or a quoted extended bus name with a minus sign preceding the first character, the ratio is adjusted as if bus |CONT2| is on the winding two side of the transformer. CONT2 = 0 by default.


• Off-nominal turns ratio in pu of winding two bus base voltage when |COD2| is 1 or 2 and CW is 1; RMA2 = 1.1 and RMI2 = 0.9 by default.

• Actual winding two voltage in kV when |COD2| is 1 or 2 and CW is 2. No default is allowed.


• Not used when |COD2| is 0; RMA2 = 1.1 and RMI2 = 0.9 by default.



• Reactive power flow into the transformer at the winding two bus end in Mvar when |COD2| is 2. No default is allowed.

• Active power flow into the transformer at the winding two bus end in MW when |COD2| is 3. No default is allowed.

• Not used when |COD2| is 0; VMA2 = 1.1 and VMI2 = 0.9 by default.






The fifth data record is specified only for three-winding transformers:

WINDV3 The winding three off-nominal turns ratio in pu of winding three bus base voltage when CW is 1; WINDV3 = 1.0 by default. WINDV3 is the actual winding three voltage in kV when CW is 2; WINDV3 is equal to the base voltage of bus K by default.

NOMV3 The nominal (rated) winding three voltage in kV, or zero to indicate that nom-inal winding three voltage is to be taken as the base voltage of bus K. NOMV3 is present for information purposes only; it is not used in any of the calculations for modeling the transformer. NOMV3 = 0.0 by default.

ANG3 The winding three phase shift angle in degrees. ANG3 is positive for a positive phase shift from the winding three side to the "T" (or “star”) point bus. ANG3 must be greater than -180.0 and less than or equal to +180.0. ANG3 = 0.0 by default.

RATA3, RATB3, The third winding’s three ratings entered in MVA (not current expressed inRATC3 MVA). RATA3 = 0.0, RATB3 = 0.0 and RATC3 = 0.0 (bypass flow limit

check for this transformer winding) by default.

COD3 The transformer control mode for automatic adjustments of the winding three tap or phase shift angle during power flow solutions: 0 for no control (fixed tap and phase shift); ±1 for voltage control; ±2 for reactive power flow control; ±3 for active power flow control. If the control mode is entered as a positive number, automatic adjustment of this transformer winding is enabled when the corresponding adjustment is activated during power flow solutions; a negative control mode suppresses the automatic adjustment of this transformer winding. COD3 = 0 by default.





CONT3 may specify a bus other than I, J, or K; in this case, the sign of CONT3 defines the location of the controlled bus relative to the transformer winding. If CONT3 is entered as a positive number, or a quoted extended bus name, the ratio is adjusted as if bus CONT3 is on the winding one or winding two side of the transformer; if CONT3 is entered as a negative number, or a quoted extended bus name with a minus sign preceding the first character, the ratio is adjusted as if bus |CONT3| is on the winding three side of the transformer. CONT3 = 0 by default.


• Off-nominal turns ratio in pu of winding three bus base voltage when |COD3| is 1 or 2 and CW is 1; RMA3 = 1.1 and RMI3 = 0.9 by default.

• Actual winding three voltage in kV when |COD3| is 1 or 2 and CW is 2. No default is allowed.


• Not used when |COD3| is 0; RMA3 = 1.1 and RMI3 = 0.9 by default.



• Reactive power flow into the transformer at the winding three bus end in Mvar when |COD3| is 2. No default is allowed.

• Active power flow into the transformer at the winding three bus end in MW when |COD3| is 3. No default is allowed.

• Not used when |COD3| is 0; VMA3 = 1.1 and VMI3 = 0.9 by default.




When specifying a two-winding transformer between buses I and J with circuit identifier CKT, if a nontransformer branch between buses I and J with a circuit identifier of CKT is already present in the working case, it is replaced (i.e., the nontransformer branch is deleted from the working case and the newly specified two-winding transformer is then added to the working case).

Transformer data input is terminated with a record specifying a winding one bus number of zero.



4.1.1.7 Area Interchange Data

Area identifiers and interchange control parameters are specified in area interchange data records. Data for each interchange area may be specified either at the time of raw data input or subsequently via activities CHNG or XLIS, or the data editor windows. Each area interchange data record has the following format:

I, ISW, PDES, PTOL, 'ARNAME'

where:

I Area number (1 through the maximum number of areas at the current size level; see Table P-1).

ISW Bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the area slack bus for area interchange control. The bus must be a generator (type two) bus in the specified area. Any area containing a system swing bus (type three) must have either that swing bus or a bus number of zero specified for its area slack bus number. Any area with an area slack bus number of zero is considered a "floating area" by the area interchange control option of the power flow solution activities. ISW = 0 by default.

PDES Desired net interchange leaving the area (export); entered in MW. PDES must be specified such that is consistent with the area interchange definition implied by the area interchange control code (tie lines only, or tie lines and loads) to be specified during power flow solutions (see Sections 4.10.3 and 4.10.3.3). PDES = 0.0 by default.

PTOL Interchange tolerance bandwidth; entered in MW. PTOL = 10.0 by default.

ARNAME Alphanumeric identifier assigned to area I. The name may contain up to twelve characters and must be enclosed in single quotes. ARNAME may be any combi-nation of blanks, uppercase letters, numbers, and special characters. ARNAME is set to twelve blanks by default.

Refer to Section 4.10.3.3 for further discussion on the area interchange control option of the power flow solution activities.

Area interchange data input is terminated with a record specifying an area number of zero.

4.1.1.8 Two-Terminal dc Transmission Line Data

Each two-terminal dc transmission line to be represented in PSS/E is introduced by reading three consecutive data records. Each set of dc line data records has the following format:

I,MDC,RDC,SETVL,VSCHD,VCMOD,RCOMP,DELTI,METER,DCVMIN,CCCITMX,CCCACCIPR,NBR,ALFMX,ALFMN,RCR,XCR,EBASR,TRR,TAPR,TMXR,TMNR,STPR,ICR,IFR,ITR,IDR,XCAPRIPI,NBI,GAMMX,GAMMN,RCI,XCI,EBASI,TRI,TAPI,TMXI,TMNI,STPI,ICI,IFI,ITI,IDI,XCAPI

The first of the three dc line data records defines the following line quantities and control parameters:

I The dc line number.




MDC Control mode: 0 for blocked, 1 for power, 2 for current. MDC = 0 by default.

RDC The dc line resistance; entered in ohms. No default allowed.

SETVL Current (amps) or power (MW) demand. When MDC is one, a positive value of SETVL specifies desired power at the rectifier and a negative value specifies desired inverter power. No default allowed.

VSCHD Scheduled compounded dc voltage; entered in kV. No default allowed.

VCMOD Mode switch dc voltage; entered in kV. When the inverter dc voltage falls below this value and the line is in power control mode (i.e., MDC = 1), the line switches to current control mode with a desired current corresponding to the desired power at scheduled dc voltage. VCMOD = 0.0 by default.

RCOMP Compounding resistance; entered in ohms. Gamma and/or TAPI is used to attempt to hold the compounded voltage (VDCI + DCCUR∗RCOMP) at VSCHD. To con-trol the inverter end dc voltage VDCI, set RCOMP to zero; to control the rectifier end dc voltage VDCR, set RCOMP to the dc line resistance, RDC; otherwise, set RCOMP to the appropriate fraction of RDC. RCOMP = 0.0 by default.

DELTI Margin entered in per unit of desired dc power or current. This is the fraction by which the order is reduced when ALPHA is at its minimum and the inverter is con-trolling the line current. DELTI = 0.0 by default.

METER Metered end code of either ’R’ (for rectifier) or ’I’ (for inverter). METER = ’I’ by default.

DCVMIN Minimum compounded dc voltage; entered in kV. Only used in constant gamma operation (i.e., when GAMMX = GAMMN) when TAPI is held constant and an ac transformer tap is adjusted to control dc voltage (i.e., when IFI, ITI, and IDI specify a two-winding transformer). DCVMIN = 0.0 by default.

CCCITMX Iteration limit for capacitor commutated two-terminal dc line Newton solution pro-cedure. CCCITMX = 20 by default.

CCCACC Acceleration factor for capacitor commutated two-terminal dc line Newton solu-tion procedure. CCCACC = 1.0 by default.

The second of the three dc line data records defines rectifier end data quantities and control parameters:

IPR Rectifier converter bus number, or extended bus name enclosed in single quotes (see Section 4.1.2). No default allowed.

NBR Number of bridges in series (rectifier). No default allowed.

ALFMX Nominal maximum rectifier firing angle; entered in degrees. No default allowed.

ALFMN Minimum steady-state rectifier firing angle; entered in degrees. No default allowed.



RCR Rectifier commutating transformer resistance per bridge; entered in ohms. No default allowed.

XCR Rectifier commutating transformer reactance per bridge; entered in ohms. No default allowed.

EBASR Rectifier primary base ac voltage; entered in kV. No default allowed.

TRR Rectifier transformer ratio. TRR = 1.0 by default.

TAPR Rectifier tap setting. TAPR = 1.0 by default.

TMXR Maximum rectifier tap setting. TMXR = 1.5 by default.

TMNR Minimum rectifier tap setting. TMNR = 0.51 by default.

STPR Rectifier tap step; must be positive. STPR = 0.00625 by default.

ICR Rectifier firing angle measuring bus number, or extended bus name enclosed in single quotes (see Section 4.1.2). The firing angle and angle limits used inside the dc model are adjusted by the difference between the phase angles at this bus and the ac/dc interface (i.e., the converter bus, IPR). ICR = 0 by default.

IFR Winding one side "from bus" number, or extended bus name enclosed in single quotes (see Section 4.1.2), of a two-winding transformer. IFR = 0 by default.

ITR Winding two side "to bus" number, or extended bus name enclosed in single quotes (see Section 4.1.2), of a two-winding transformer. ITR = 0 by default.

IDR Circuit identifier; the branch described by IFR, ITR, and IDR must have been entered as a two-winding transformer; an ac transformer may control at most only one dc converter. IDR = '1' by default.

If no branch is specified, TAPR is adjusted to keep alpha within limits; otherwise, TAPR is held fixed and this transformer’s tap ratio is adjusted. The adjustment logic assumes that the rectifier converter bus is on the winding two side of the transformer. The limits TMXR and TMNR specified here are used; except for the transformer con-trol mode flag (COD of Section 4.1.1.6), the ac tap adjustment data is ignored.

XCAPR Commutating capacitor reactance magnitude per bridge; entered in ohms. XCAPR = 0.0 by default.

Data on the third of the three dc line data records contains the inverter quantities corresponding to the rectifier quantities specified on the second record described above.

Dc line converter buses, IPR and IPI, may be type one, two, or three buses. Generators, loads, fixed and switched shunt elements, other dc line converters, and FACTS device sending ends are per-mitted at converter buses.

When either XCAPR > 0.0 or XCAPI > 0.0, the two-terminal dc line is treated as capacitor com-mutated. Capacitor commutated two-terminal dc lines preclude the use of a remote ac transformer




as commutation transformer tap and remote commutation angle buses at either converter. Any data provided in these fields are ignored for capacitor commutated two-terminal dc lines.

Further details on dc line modeling in power flow solutions are given in Section 4.8.6.

Dc line data input is terminated with a record specifying a dc line number of zero.

4.1.1.9 Voltage Source Converter (VSC) Dc Line Data

Each voltage source converter (VSC) dc line to be represented in PSS/E is introduced by reading a set of three consecutive data records. Each set of VSC dc line data records has the following format:

'NAME', MDC, RDC, O1, F1, ... O4, F4 IBUS,TYPE,MODE,DCSET,ACSET,ALOSS,BLOSS,MINLOSS,SMAX,IMAX,PWF,MAXQ,MINQ,REMOT,RMPCT IBUS,TYPE,MODE,DCSET,ACSET,ALOSS,BLOSS,MINLOSS,SMAX,IMAX,PWF,MAXQ,MINQ,REMOT,RMPCT

The first of the three VSC dc line data records defines the following line quantities and control parameters:

NAME The non-blank alphanumeric identifier assigned to this VSC dc line. Each VSC dc line must have a unique NAME. The name may be up to twelve characters and must be enclosed in single quotes. NAME may contain any combination of blanks, uppercase letters, numbers and special characters. No default allowed.

MDC Control mode: 0 for out-of-service, 1 for in-service. MDC = 1 by default.

RDC The dc line resistance; entered in ohms. RDC must be positive. No default allowed.

Oi An owner number (1 through the maximum number of owners at the current size level; see Table P-1). Each VSC dc line may have up to four owners. By default, O1 is 1, and O2, O3 and O4 are zero.

Fi The fraction of total ownership assigned to owner Oi; each Fi must be positive. The Fi values are normalized such that they sum to 1.0 before they are placed in the working case. By default, each Fi is 1.0.

The remaining two data records define the converter buses (converter 1 and converter 2), along with their data quantities and control parameters:

IBUS Converter bus number, or extended bus name enclosed in single quotes (see Section 4.1.2). No default allowed.

TYPE Code for the type of converter dc control: 0 for converter out-of-service, 1 for dc voltage control, or 2 for MW control. When both converters are in-service, exactly one converter of each VSC dc line must be TYPE 1. No default allowed.

MODE Converter ac control mode: 1 for ac voltage control or 2 for fixed ac power factor. MODE = 1 by default.

DCSET Converter dc setpoint. For TYPE = 1, DCSET is the scheduled dc voltage on the dc side of the converter bus; entered in kV. For TYPE = 2, DCSET is the power demand, where a positive value specifies that the converter is feeding active power



into the ac network at bus IBUS, and a negative value specifies that the converter is withdrawing active power from the ac network at bus IBUS; entered in MW. No default allowed.

ACSET Converter ac setpoint. For MODE = 1, ACSET is the regulated ac voltage setpoint; entered in pu. For MODE = 2, ACSET is the power factor setpoint. ACSET = 1.0 by default.

Aloss, Bloss Coefficients of the linear equation used to calculate converter losses:

KWconv loss = Aloss + Idc*Bloss

Aloss is entered in kW. Bloss is entered in kW/amp. Aloss = Bloss = 0.0 by default.

MINloss Minimum converter losses; entered in kW. MINloss = 0.0 by default.

SMAX Converter MVA rating; entered in MVA. SMAX = 0.0 to allow unlimited con-verter MVA loading. SMAX = 0.0 by default.

IMAX Converter ac current rating; entered in amps. IMAX = 0.0 to allow unlimited con-verter current loading. If a positive IMAX is specified, the base voltage assigned to bus IBUS must be positive. IMAX = 0.0 by default.

PWF Power weighting factor fraction (0.0 < PWF < 1.0) used in reducing the active power order and either the reactive power order (when MODE is 2) or the reactive power limits (when MODE is 1) when the converter MVA or current rating is vio-lated. When PWF is 0.0, only the active power is reduced; when PWF is 1.0, only the reactive power is reduced; otherwise, a weighted reduction of both active and reactive power is applied. PWF = 1.0 by default.

MAXQ Reactive power upper limit; entered in Mvar. A positive value of reactive power indicates reactive power flowing into the ac network from the converter; a negative value of reactive power indicates reactive power withdrawn from the ac network. Not used if MODE = 2. MAXQ = 9999.0 by default.

MINQ Reactive power lower limit; entered in Mvar. A positive value of reactive power indicates reactive power flowing into the ac network from the converter; a negative value of reactive power indicates reactive power withdrawn from the ac network. Not used if MODE = 2. MINQ = -9999.0 by default.

REMOT Bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of a remote type 1 or 2 bus whose voltage is to be regulated by this converter to the value specified by ACSET. If bus REMOT is other than a type 1 or 2 bus, bus IBUS regulates its own voltage to the value specified by ACSET. REMOT is entered as zero if the converter is to regulate its own voltage. Not used if MODE = 2. REMOT = 0 by default.




RMPCT Percent of the total Mvar required to hold the voltage at the bus controlled by bus IBUS that are to be contributed by this VSC; RMPCT must be positive. RMPCT is needed only if REMOT specifies a valid remote bus and there is more than one local or remote voltage controlling device (plant, switched shunt, FACTS device shunt element, or VSC dc line converter) controlling the voltage at bus REMOT to a setpoint, or REMOT is zero but bus IBUS is the controlled bus, local or remote, of one or more other setpoint mode voltage controlling devices. Not used if MODE = 2. RMPCT = 100.0 by default.

Each VSC dc line converter bus:

• must be a type one or two bus. Generators, loads, fixed and switched shunt elements, other dc line converters, and FACTS device sending ends are permitted at converter buses.

• must not have the terminal end of a FACTS device connected to the same bus.

• must not be connected by a zero impedance line to another bus which violates any of the above restrictions.

In specifying reactive power limits for converters which control ac voltage (i.e., those with unequal reactive power limits whose MODE is 1), the use of very narrow var limit bands is discouraged. The Newton-Raphson based power flow solutions require that the difference between the control-ling equipment's high and low reactive power limits be greater than 0.002 pu for all setpoint mode voltage controlling equipment (0.2 Mvar on a 100 MVA system base). It is recommended that voltage controlling VSC converters have Mvar ranges substantially wider than this minimum per-missible range.

For interchange and loss assignment purposes, the dc voltage controlling converter is assumed to be the non-metered end of each VSC dc line. As with other network branches, losses are assigned to the subsystem of the non-metered end, and flows at the metered ends are used in interchange calculations.


VSC dc line data input is terminated with a record specifying a blank dc line name (’ ’) or a dc line name of ’0’.

4.1.1.10 Switched Shunt Data

Each network bus to be represented in PSS/E with switched shunt admittance devices must have a switched shunt data record specified for it. The switched shunts are represented with up to eight blocks of admittance, each one of which consists of up to nine steps of the specified block admit-tance. Each switched shunt data record has the following format:

I, MODSW, VSWHI, VSWLO, SWREM, RMPCT, ’RMIDNT’, BINIT, N1, B1, N2, B2, ... N8, B8

where:




MODSW Control mode: 0 - fixed1 - discrete adjustment, controlling voltage locally or at bus SWREM2 - continuous adjustment, controlling voltage locally or at bus SWREM3 - discrete adjustment, controlling reactive power output of the plant at bus SWREM4 - discrete adjustment, controlling reactive power output of the VSC dc line converter at bus SWREM of the VSC dc line whose name is specified as RMIDNT5 - discrete adjustment, controlling admittance setting of the switched shunt at bus SWREMMODSW = 1 by default.

VSWHI When MODSW is 1 or 2, the controlled voltage upper limit; entered in pu.

When MODSW is 3, 4 or 5, the controlled reactive power range upper limit; entered in pu of the total reactive power range of the controlled voltage controlling device.

VSWHI is not used when MODSW is 0. VSWHI = 1.0 by default.

VSWLO When MODSW is 1 or 2, the controlled voltage lower limit; entered in pu.

When MODSW is 3, 4 or 5, the controlled reactive power range lower limit; entered in pu of the total reactive power range of the controlled voltage controlling device.

VSWLO is not used when MODSW is 0. VSWLO = 1.0 by default.

SWREM Bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the bus whose voltage or connected equipment reactive power output is con-trolled by this switched shunt.

When MODSW is 1 or 2, SWREM is entered as 0 if the switched shunt is to regu-late its own voltage; otherwise, SWREM specifies the remote type one or two bus whose voltage is to be regulated by this switched shunt.

When MODSW is 3, SWREM specifies the type two or three bus whose plant reac-tive power output is to be regulated by this switched shunt. Set SWREM to "I" if the switched shunt and the plant which it controls are connected to the same bus.

When MODSW is 4, SWREM specifies the converter bus of a VSC dc line whose converter reactive power output is to be regulated by this switched shunt. Set SWREM to "I" if the switched shunt and the VSC dc line converter which it con-trols are connected to the same bus.

When MODSW is 5, SWREM specifies the remote bus to which the switched shunt whose admittance setting is to be regulated by this switched shunt is connected.

SWREM is not used when MODSW is 0. SWREM = 0 by default.




RMPCT Percent of the total Mvar required to hold the voltage at the bus controlled by bus I that are to be contributed by this switched shunt; RMPCT must be positive. RMPCT is needed only if SWREM specifies a valid remote bus and there is more than one local or remote voltage controlling device (plant, switched shunt, FACTS device shunt element, or VSC dc line converter) controlling the voltage at bus SWREM to a setpoint, or SWREM is zero but bus I is the controlled bus, local or remote, of one or more other setpoint mode voltage controlling devices. Only used if MODSW = 1 or 2. RMPCT = 100.0 by default.

RMIDNT When MODSW is 4, the name of the VSC dc line whose converter bus is specified in SWREM. RMIDNT is not used for other values of MODSW. RMIDNT is a blank name by default.

BINIT Initial switched shunt admittance; entered in Mvar at unity voltage. BINIT = 0.0 by default.

Ni Number of steps for block i. The first zero value of Ni or Bi is interpreted as the end of the switched shunt blocks for bus I. Ni = 0 by default.

Bi Admittance increment for each of Ni steps in block i; entered in Mvar at unity voltage. Bi = 0.0 by default.

BINIT needs to be set to its actual solved case value only when the network, as entered into the working case via activity READ, is to be considered solved as read in, or when the device is to be treated as "fixed" (i.e., MODSW is set to zero or switched shunts are to be locked during power flow solutions).

The switched shunt elements at a bus may consist entirely of reactors (each Bi is a negative quan-tity) or entirely of capacitor banks (each Bi is a positive quantity). In these cases, the shunt blocks are specified in the order in which they are switched on the bus.

If the switched shunt devices at a bus are a mixture of reactors and capacitors, the reactor blocks are specified first in the order in which they are switched on, followed by the capacitor blocks in the order in which they are switched on.

In specifying reactive power limits for setpoint mode voltage controlling switched shunts (i.e., those with MODSW of 1 or 2), the use of a very narrow admittance range is discouraged. The Newton-Raphson based power flow solutions require that the difference between the controlling equipment's high and low reactive power limits be greater than 0.002 pu for all setpoint mode voltage controlling equipment (0.2 Mvar on a 100 MVA system base). It is recommended that voltage controlling switched shunts have admittance ranges substantially wider than this minimum permissible range.

When MODSW is 3, 4 or 5, VSWLO and VSWHI define a restricted band of the controlled device’s reactive power range. They are specified in pu of the total reactive power range of the controlled device (i.e., the plant QMAX - QMIN when MODSW is 3, MAXQ - MINQ of a VSC dc line con-verter when MODSW is 4, and ΣNiBi − ΣNjBj when MODSW is 5, where "i" are those switched shunt blocks for which Bi is positive and "j" are those for which Bi is negative). VSWLO must be greater than 0.0 and less than VSWHI, and VSWHI must be less than 1.0. That is, the following relationship must be honored:

0.0 < VSWLO < VSWHI < 1.0



The reactive power band for switched shunt control is calculated by applying VSWLO and VSWHI to the reactive power band extremes of the controlled plant or VSC converter. For example, with MINQ of -50.0 and MAXQ of +50.0, if VSWLO is 0.2 and VSWHI is 0.75, then the reactive power band defined by VSWLO and VSWHI is:

-50.0 + 0.2*(50.0 - (-50.0)) = -50.0 + 0.2*100.0 = -50.0 + 20.0 = -30.0 Mvar

through:

-50.0 + 0.75*(50.0 - (-50.0)) = -50.0 + 0.75*100.0 = -50.0 + 75.0 = +25.0 Mvar

The switched shunt admittance is kept in the working case and reported in output tabulations sepa-rately from the fixed bus shunt, which is input on the bus data record (see Section 4.1.1.2).

Refer to Sections 4.8.4, 4.8.6 and 4.10.3.4 for details on the handling of switched shunts during power flow solutions.

It is recommended that data records for switched shunts whose control mode is 5 (i.e., they control the setting of other switched shunts) be grouped together following all other switched shunt data records. This practice will eliminate any warnings of no switched shunt at the specified remote bus simply because the remote bus’ switched shunt record has not as yet been read.

Switched shunt data input is terminated with a record specifying a bus number of zero.

4.1.1.11 Transformer Impedance Correction Tables

Transformer impedance correction tables are used to model a change of transformer impedance as off-nominal turns ratio or phase shift angle is adjusted. Data for each table may be specified either at the time of raw data input or subsequently via activity CHNG or the impedance correction table data editor window. Each transformer impedance correction data record has the following format:

I, T1, F1, T2, F2, T3, F3, ... T11, F11

where:

I Impedance correction table number.

Ti Either off-nominal turns ratio in pu or phase shift angle in degrees. Ti = 0.0 by default.

Fi Scaling factor by which transformer nominal impedance is to be multiplied to obtain the actual transformer impedance for the corresponding "Ti". Fi = 0.0 by default.

The "Ti" values on a transformer impedance correction table record must all be either tap ratios or phase shift angles. They must be entered in strictly ascending order; i.e., for each "i", Ti+1>Ti. Each "Fi" entered must be greater than zero. On each record, at least 2 pairs of values must be specified and up to 11 may be entered.




The Ti values for tables that are a function of tap ratio (rather than phase shift angle) are in units of the controlling winding’s off-nominal turns ratio in pu of the controlling winding’s bus base voltage.

A transformer winding is assigned to an impedance correction table either on the third, fourth or fifth record of the transformer data record block of activities READ, TREA, RDCH (see Section 4.1.1.6), or via activities CHNG or XLIS, or the data editor windows. Each table may be shared among many transformer windings. If the first "T" in a table is less than 0.5 or the last "T" entered is greater than 1.5, "T" is assumed to be the phase shift angle and the impedance of each transformer winding assigned to the table is treated as a function of phase shift angle. Otherwise, the impedances of the transformer windings assigned to the table are made sensitive to off-nominal turns ratio.

The working case provides for the storage of both a nominal and actual impedance for each trans-former winding impedance. The value of transformer impedance entered in activities READ, TREA, RDCH, CHNG, or XLIS, and in the data editor windows is taken as the nominal value of impedance. Each time the complex tap ratio of a transformer is changed, either automatically by the power flow solution activities or manually by the user, and the transformer winding has been assigned to an impedance correction table, actual transformer winding impedance is redetermined if appropriate. First, the scaling factor is established from the appropriate table by linear interpola-tion; then nominal impedance is multiplied by the scaling factor to determine actual impedance. An appropriate message is printed any time the actual impedance is modified.

Transformer impedance correction data input is terminated with a record specifying a table number of zero.

4.1.1.12 Multiterminal dc Transmission Line Data

Each multiterminal dc transmission line to be represented in PSS/E is introduced by reading a series of data records. Each set of multiterminal dc line data records begins with a record of the following format:

I, NCONV, NDCBS, NDCLN, MDC, VCONV, VCMOD, VCONVN

where:

I Multiterminal dc line number.

NCONV Number of ac converter station buses in multiterminal dc line "I". No default allowed.

NDCBS Number of "dc buses" in multiterminal dc line "I" (NCONV < NDCBS). No default allowed.

NDCLN Number of dc links in multiterminal dc line "I". No default allowed.

MDC Control mode: 0 - blocked1 - power2 - currentMDC = 0 by default.



VCONV Bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the ac converter station bus that controls dc voltage on the positive pole of multi-terminal dc line "I". Bus VCONV must be a positive pole inverter. No default allowed.

VCMOD Mode switch dc voltage; entered in kV. When any inverter dc voltage magnitude falls below this value and the line is in power control mode (i.e., MDC = 1), the line switches to current control mode with converter current setpoints corre-sponding to their desired powers at scheduled dc voltage. VCMOD = 0.0 by default.

VCONVN Bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), of the ac converter station bus that controls dc voltage on the negative pole of multiterminal dc line "I". If any negative pole converters are specified (see below), bus VCONVN must be a negative pole inverter. If the negative pole is not being modeled, VCONVN must be specified as zero. VCONVN = 0 by default.

This data record is followed by "NCONV" converter records of the following format:

IB,N,ANGMX,ANGMN,RC,XC,EBAS,TR,TAP,TPMX,TPMN,TSTP,SETVL,DCPF,MARG,CNVCOD

where:

IB Ac converter bus number, or extended bus name enclosed in single quotes (see Section 4.1.2). No default allowed.

N Number of bridges in series. No default allowed.

ANGMX Nominal maximum ALPHA or GAMMA angle; entered in degrees. No default allowed.

ANGMN Minimum steady-state ALPHA or GAMMA angle; entered in degrees. No default allowed.

RC Commutating resistance per bridge; entered in ohms. No default allowed.

XC Commutating reactance per bridge; entered in ohms. No default allowed.

EBAS Primary base ac voltage; entered in kV. No default allowed.

TR Actual transformer ratio. TR = 1.0 by default.

TAP Tap setting. TAP = 1.0 by default.

TPMX Maximum tap setting. TPMX = 1.5 by default.

TPMN Minimum tap setting. TPMN = 0.51 by default.

TSTP Tap step; must be positive. TSTP = 0.00625 by default.




SETVL Converter setpoint. When IB is equal to VCONV or VCONVN, SETVL specifies the scheduled dc voltage magnitude, entered in kV, across the converter. For other converter buses, SETVL contains the converter current (amps) or power (MW) demand; a positive value of SETVL indicates that bus IB is a rectifier, and a neg-ative value indicates an inverter. No default allowed.

DCPF Converter "participation factor." When the order at any rectifier in the multi-terminal dc line is reduced, either to maximum current or margin, the orders at the remaining converters on the same pole are modified according to their DCPFs to:

SETVL + (DCPF/SUM)∗R

where SUM is the sum of the DCPFs at the unconstrained converters on the same pole as the constrained rectifier, and R is the order reduction at the constrained rec-tifier. DCPF = 1. by default.

MARG Rectifier margin entered in per unit of desired dc power or current. The converter order reduced by this fraction, (1.-MARG)∗SETVL, defines the minimum order for this rectifier. MARG is used only at rectifiers. MARG = 0.0 by default.

CNVCOD Converter code. A positive value or zero must be entered if the converter is on the positive pole of multiterminal dc line "I". A negative value must be entered for negative pole converters. CNVCOD = 1 by default.

These data records are followed by "NDCBS" dc bus records of the following format:

IDC, IB, IA, ZONE, 'NAME', IDC2, RGRND, OWNER

where:

IDC Dc bus number (1 to NDCBS). The dc buses are used internally within each mul-titerminal dc line and must be numbered 1 through NDCBS. No default allowed.

IB Ac converter bus number, or extended bus name enclosed in single quotes (see Section 4.1.2), or zero. Each converter station bus specified in a converter record must be specified as IB in exactly one dc bus record. Dc buses that are connected only to other dc buses by dc links and not to any ac converter buses must have a zero specified for IB. A dc bus specified as IDC2 on one or more other dc bus records must have a zero specified for IB on its own dc bus record. IB = 0 by default.

IA Area number (1 through the maximum number of areas at the current size level; see Table P-1). IA = 1 by default.

ZONE Zone number (1 through the maximum number of zones at the current size level; see Table P-1). ZONE = 1 by default.

NAME Alphanumeric identifier assigned to dc bus "IDC". The name may be up to twelve characters and must be enclosed in single quotes. NAME may contain any combi-nation of blanks, uppercase letters, numbers, and special characters. NAME is twelve blanks by default.



IDC2 Second dc bus to which converter IB is connected, or zero if the converter is con-nected directly to ground. For voltage controlling converters, this is the dc bus with the lower dc voltage magnitude and SETVL specifies the voltage difference between buses IDC and IDC2. For rectifiers, dc buses should be specified such that power flows from bus IDC2 to bus IDC. For inverters, dc buses should be specified such that power flows from bus IDC to bus IDC2. IDC2 is ignored on those dc bus records that have IB specified as zero. IDC2 = 0 by default.

RGRND Resistance to ground at dc bus IDC; entered in ohms. During solutions RGRND is used only for those dc buses specified as IDC2 on other dc bus records. RGRND = 0.0 by default.


These data records are followed by "NDCLN" dc link records of the following format:

IDC, JDC, DCCKT, RDC, LDC

where:

IDC Branch "from bus" dc bus number.

JDC Branch "to bus" dc bus number. JDC is entered as a negative number to designate it as the metered end for area and zone interchange calculations. Otherwise, bus IDC is assumed to be the metered end.

DCCKT One-character uppercase alphanumeric branch circuit identifier. It is recommended that single circuit branches be designated as having the circuit identifier ’1’. DCCKT = ’1’ by default.

RDC Dc link resistance, entered in ohms. No default allowed.

LDC Dc link inductance, entered in mH. LDC is not used by the power flow solution activities but is available to multiterminal dc line dynamics models. LDC = 0.0 by default.

The following points should be noted in specifying multiterminal dc line data:

1. Conventional two-terminal (see Section 4.1.1.8) and multiterminal dc lines are stored separately in PSS/E working memory. Therefore, there may simultaneously exist, for example, a two-terminal dc line identified as dc line number 1 along with a multiter-minal line numbered 1.

2. Multiterminal lines should have at least three converter terminals; conventional dc lines consisting of two terminals should be modeled as two-terminal lines (see Section 4.1.1.8).




3. Ac converter buses may be type one, two, or three buses. Generators, loads, fixed and switched shunt elements, other dc line converters, and FACTS device sending ends are permitted at converter buses.

4. Each multiterminal dc line is treated as a subnetwork of "dc buses" and "dc links" con-necting its ac converter buses. For each multiterminal dc line, the dc buses must be numbered 1 through NDCBS.

5. Each ac converter bus must be specified as IB on exactly one dc bus record; there may be dc buses connected only to other dc buses by dc links but not to any ac converter bus.

6. Ac converter bus "IB" may be connected to a dc bus "IDC", which is connected directly to ground. "IB" is specified on the dc bus record for dc bus "IDC"; the IDC2 field is specified as zero.

7. Alternatively, ac converter bus "IB" may be connected to two dc buses "IDC" and "IDC2", the second of which is connected to ground through a specified resistance. "IB" and "IDC2" are specified on the dc bus record for dc bus "IDC"; on the dc bus record for bus "IDC2", the ac converter bus and second dc bus fields (IB and IDC2, respectively) must be specified as zero and the grounding resistance is specified as RGRND.

8. The same dc bus may be specified as the second dc bus for more than one ac converter bus.

9. All dc buses within a multiterminal dc line must be reachable from any other point within the subnetwork.

10. The area number assigned to dc buses and the metered end designation of dc links are used in calculating area interchange and assigning losses in activities AREA, INTA, TIES, and SUBS as well as in the interchange control option of the power flow solution activities. Similarly, the zone assignment and metered end specification is used in activities ZONE, INTZ, TIEZ, and SUBS.

11. Section 4.3.2 describes the specification of NCONV, NDCBS and NDCLN when spec-ifying changes to an existing multi-terminal dc line in activity RDCH


Multiterminal dc line data input is terminated with a record specifying a dc line number of zero.

4.1.1.13 Multisection Line Grouping Data

Each multisection line grouping to be represented in PSS/E is introduced by reading a multisection line grouping data record. Each multisection line grouping data record has the following format:

I, J, ID, DUM1, DUM2, ... DUM9

where:

I "From bus" number, or extended bus name enclosed in single quotes (see Section 4.1.2).



J "To bus" number, or extended bus name enclosed in single quotes (see Section 4.1.2). J is entered as a negative number or with a minus sign before the first character of the extended bus name to designate it as the metered end; other-wise, bus I is assumed to be the metered end.

ID Two-character upper case alphanumeric multisection line grouping identifier. The first character must be an ampersand ("&"). ID = ’&1’ by default.

DUMi Bus numbers, or extended bus names enclosed in single quotes (see Section 4.1.2), of the "dummy buses" connected by the branches that comprise this multisection line grouping. No defaults allowed.

The "DUMi" values on each record define the branches connecting bus I to bus J, and are entered so as to trace the path from bus I to bus J. Specifically, for a multisection line grouping consisting of three "line sections" (and hence two "dummy buses"):

The path from "I" to "J" is defined by the following branches:

If this multisection line grouping is to be assigned the line identifier "&1", the corresponding multi-section line grouping data record is given by:

I J &1 D1 D2

Up to 10 line sections (and hence 9 dummy buses) may be defined in each multisection line grouping. A branch may be a line section of at most one multisection line grouping.

Each dummy bus must have exactly two branches connected to it, both of which must be members of the same multisection line grouping. A multisection line dummy bus may not be a converter bus of a dc transmission line. A FACTS control device may not be connected to a multisection line dummy bus.

The status of line sections and type codes of dummy buses are set such that the multisection line is treated as a single entity with regards to its service status.

When the multisection line reporting option is enabled (see Sections 3.11 and 6.10), several power flow reporting activities such as POUT and LOUT do not tabulate conditions at multisection line dummy buses. Accordingly, care must be taken in interpreting power flow output reports when dummy buses are other than passive nodes (e.g., if load or generation is present at a dummy bus).

From To Circuit

I D1 C1

D1 D2 C2

D2 J C3

C1 C2 C3

I JD1 D2




Multisection line grouping data input is terminated with a record specifying a "from bus" number of zero.

4.1.1.14 Zone Data

Zone identifiers are specified in zone data records. Data for each zone may be specified either at the time of raw data input or subsequently via activities CHNG or XLIS, or the data editor windows. Each zone data record has the following format:

I, 'ZONAME'

where:

I Zone number (1 through the maximum number of zones at the current size level; see Table P-1).

ZONAME Alphanumeric identifier assigned to zone I. The name may contain up to twelve characters and must be enclosed in single quotes. ZONAME may be any combi-nation of blanks, uppercase letters, numbers, and special characters. ZONAME is set to twelve blanks by default.

Zone data input is terminated with a record specifying a zone number of zero.

4.1.1.15 Interarea Transfer Data

Scheduled active power transfers between pairs of areas are specified in interarea transfer data records. Each interarea transfer data record has the following format:

ARFROM, ARTO, TRID, PTRAN

where:

ARFROM "From area" number (1 through the maximum number of areas at the current size level; see Table P-1).

ARTO "To area" number (1 through the maximum number of areas at the current size level; see Table P-1).

TRID Single-character (0 through 9 or A through Z) upper case interarea transfer identi-fier used to distinguish among multiple transfers between areas ARFROM and ARTO. TRID = ’1’ by default.

PTRAN MW comprising this transfer. A positive PTRAN indicates that area ARFROM is selling to area ARTO. PTRAN = 0.0 by default.

Following the completion of interarea transfer data input, activity READ alarms any area for which at least one interarea transfer is present and whose "sum of transfers" differs from its desired net interchange, PDES (see Section 4.1.1.7).

Interarea transfer data input is terminated with a record specifying a from area number of zero.



4.1.1.16 Owner Data

Owner identifiers are specified in owner data records. Data for each owner may be specified either at the time of raw data input or subsequently via activities CHNG or XLIS, or the data editor win-dows. Each owner data record has the following format:

I, 'OWNAME'

where:

I Owner number (1 through the maximum number of owners at the current size level; see Table P-1).

OWNAME Alphanumeric identifier assigned to owner I. The name may contain up to twelve characters and must be enclosed in single quotes. OWNAME may be any combi-nation of blanks, uppercase letters, numbers, and special characters. OWNAME is set to twelve blanks by default.

Owner data input is terminated with a record specifying an owner number of zero.

4.1.1.17 FACTS Device Data

Each FACTS (Flexible AC Transmission System) device to be represented in PSS/E is specified in FACTS device data records. Each FACTS device data record has the following format:

N,I,J,MODE,PDES,QDES,VSET,SHMX,TRMX,VTMN,VTMX,VSMX,IMX,LINX,RMPCT,OWNER,SET1,SET2,VSREF

where:

N FACTS device number.

I Sending end bus number, or extended bus name enclosed in single quotes (see Section 4.1.2). No default allowed.

J Terminal end bus number, or extended bus name enclosed in single quotes (see Section 4.1.2); 0 for a STATCON. J = 0 by default.

MODE Control mode: 0 - out-of-service (i.e., series and shunt links open)1 - series and shunt links operating.2 - series link bypassed (i.e., like a zero impedance line) and shunt link operating as a STATCON.3 - series and shunt links operating with series link at constant series impedance.4 - series and shunt links operating with series link at constant series voltage.5 - "master" device of an IPFC with P and Q setpoints specified; FACTS device "N+1" must be the "slave" device (i.e., its MODE is 6 or 8) of this IPFC.6 - "slave" device of an IPFC with P and Q setpoints specified; FACTS device "N-1" must be the "master" device (i.e., its MODE is 5 or 7) of this IPFC. The Q setpoint is ignored as the "master" device dictates the active power exchanged between the two devices.7 - "master" device of an IPFC with constant series voltage setpoints specified; FACTS device "N+1 must be the "slave" device (i.e., its MODE is 6 or 8) of this IPFC.




8 - "slave" device of an IPFC with constant series voltage setpoints specified; FACTS device "N-1" must be the "master" device (i.e., its MODE is 5 or 7) of this IPFC. The complex Vd + jVq setpoint is modified during power flow solutions to reflect the active power exchange determined by the "master" device.If J is specified as 0, MODE must be either 0 or 1. MODE = 1 by default.

PDES Desired active power flow arriving at the terminal end bus; entered in MW. PDES = 0.0 by default.

QDES Desired reactive power flow arriving at the terminal end bus; entered in MVAR. QDES = 0.0 by default.

VSET Voltage setpoint at the sending end bus; entered in pu. VSET = 1.0 by default.

SHMX Maximum shunt current at the sending end bus; entered in MVA at unity voltage. SHMX = 9999.0 by default.

TRMX Maximum bridge active power transfer; entered in MW. TRMX = 9999.0 by default.

VTMN Minimum voltage at the terminal end bus; entered in pu. VTMN = 0.9 by default.

VTMX Maximum voltage at the terminal end bus; entered in pu. VTMX = 1.1 by default.

VSMX Maximum series voltage; entered in pu. VSMX = 1.0 by default.

IMX Maximum series current, or zero for no series current limit; entered in MVA at unity voltage. IMX = 0.0 by default.

LINX Reactance of the dummy series element used during model solution; entered in pu. LINX = 0.05 by default.

RMPCT Percent of the total Mvar required to hold the voltage at bus I that are to be contrib-uted by the shunt element of this FACTS device; RMPCT must be positive. RMPCT is needed only if there is more than one local or remote voltage control-ling device (plant, switched shunt, FACTS device shunt element, or VSC dc line converter) controlling the voltage at bus I to a setpoint. RMPCT = 100.0 by default.


SET1,SET2 If MODE is 3, resistance and reactance respectively of the constant impedance, entered in pu; if MODE is 4, the magnitude (in pu) and angle (in degrees) of the constant series voltage with respect to the quantity indicated by VSREF; if MODE is 7 or 8, the real (Vd) and imaginary (Vq) components (in pu) of the constant series voltage with respect to the quantity indicated by VSREF; for other values of MODE, SET1 and SET2 are read, but not saved or used during power flow solu-tions. SET1 = 0.0 and SET2 = 0.0 by default.



VSREF Series voltage reference code to indicate the series voltage reference of SET1 and SET2 when MODE is 4, 7 or 8: 0 for sending end voltage, 1 for series current. VSREF = 0 by default.

An Interline Power Flow Controller (IPFC) is modeled by using two consecutively numbered series FACTS devices. The first of this pair must be assigned as the IPFC "master" device by setting its control mode to 5 or 7, and the second must be assigned as its companion IPFC "slave" device by setting its control mode to 6 or 8. In an IPFC, both devices have a series element but no shunt ele-ment. Therefore, both devices typically have SHMX set to zero, and VSET of both devices is ignored. Conditions at the "master" device define the active power exchange between the two devices.

Figure 4-2 shows the PSS/E FACTS control device model with its various setpoints and limits.

Each FACTS sending end bus must be a type 1 or 2 bus, and each terminal end bus must be a type 1 bus. Refer to Section 4.8.5 for other topological restrictions and for details on the handling of FACTS devices during the power flow solution activities.

Further details on FACTS device modeling in power flow solutions are given in Sections 4.8.5 and 4.8.7.

FACTS device data input is terminated with a record specifying a FACTS device number of zero.

Figure 4-2. FACTS Control Device Setpoints and Limits

Bus I Bus J

IMX

PDESQDES

SHM

X

TRMX

VTMXVTMN

VSET

VSMX

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